I would irrigate it with salt water first, you may have some sterile saline, this would be a good thing to use. Peroxide can destroy healthy skin cells. Don't so much "pack" it as put a piece of gauze in to wick out the drainage and keep it open so it can drain. And of course the ointment is a good thing, cover it with a dry dressing. The keflex is good too. Sometimes these things can be hard to get rid of. Be sure you take all the pills, don't stop if it seems healed, it can recur that way.